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Shielding? What's the funk-tion?


Dietrich

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Hey Cats,

 

After looking at that awesome Flying V project (see topic below, perhaps above), I caught the part about him putting copper shielding in the cavities.

 

What does this do (probably a stupid question, but indulge me)? And if the innards of my bass and guitars are just painted wood, would I improve them any by adding shielding?

 

Thanks in advance.

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Generally, the thought is to reduce noise to the electronic system. None of my guitars have that and I have no issues with noise, but they are all grounded well.

 

I've seen some really cool shielding work on this forum, but I don't know how truly valuable it is. My experience says, not. But then again I've haven't seen everything.

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On single coils it's necessary if you wanna be on the same stage as your amp or same room as any neon signs.

 

So the shielding cuts the single coil hum? Interesting....I thought the hum came from the pickup itself, not the electronics.

 

I don't have a single coil guitar anymore, so I don't see this problem with humbuckers.

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After looking at that awesome Flying V project (see topic below' date=' perhaps above), I caught the part about him putting copper shielding in the cavities.

 

What does this do (probably a stupid question, but indulge me)? And if the innards of my bass and guitars are just painted wood, would I improve them any by adding shielding?

[/quote']

 

It's called a Faradays Cage. And like a cage you can prevent the bad guys in this case capacitence(generation of current) which translates in hum, from entering, or going. The most basic form of the FC principle you probably know allready is the braided wire.

The use of a FC is not limited to SC guitars. Any noisy or hummy guitar(think high output PU) will benefit.

IMO Copper foil works best. Shieldingpaint is easiest, but requires copious amounts and is expensive.

The cage does not have to be closed perfectly to generate a good result. There is some debate whether it influences tone if used to 'cage' Single coils. I suppose it's a fair trade-off for reducing noise.

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Hey there, the main reason that I put that shielding in my Flying V was because... I had a roll of it and no other use for it! I replaced the pickguard, the original one had a strip of shielding which ran along where all the pots and switch and jack were, so I thought when I put my new pickguard on I'd just put a strip of the copper tape on. However I then decided to put a little more on... and then more until I thought I may as well finish teh reel off and make the inside look more interesting, and if it helps the sound of the guitar by 0.1% then that is a bonus. It's just for fun really - and look - it got people talking so I am happy!

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Ricochet got it right. It's a Faraday Cage, an extension of the shielding in your guitar cord, a grounded conductor that wraps the signal carrying conductors. It's used to reduce EMI (electromagnetic interference) and RFI (radio frequency interference), and is also used in secure government and corporate computer installations to reduce spy snooping from the outside (then it's called Tempest shielding).

 

Too much information, huh? The key is that it must be grounded to be effective. You can shield your pickup cavities all you want, but it must be connected to ground to be effective.

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The key is that it must be grounded to be effective. You can shield your pickup cavities all you want' date=' but it must be connected to ground to be effective.[/quote']

 

And the funny part is if the cage works well, you should be able to remove the grounding wire from/to the bridge!

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Great' date=' informative thread.

 

I see how the shield works for solid bodies, but we have a lot of semi owners with SC pups here. How would you set up a faraday's cage on a semi/SC?[/quote']

Okay, first, let's get the terminology straight. it's Faraday cage, not Faraday's cage. They are named after Faraday, they don't belong to him. :-

 

Shielding a semi-solid would be done in a similar manner. You would line the pickup cavities with copper foil; then you would need to have some kind of metal box that the controls could live in since there's no actual 'cavity' in the sense of a solid body guitar. Note that some Les Pauls have this metal box inside their control cavities. Anyway you'd have to build this box into the guitar since it won't exactly fit through the ƒ-hole; needless to say any maintenance will be impossible. Basically the only practical way to implement a Faraday cage on a thinline would require some kind of access panel in the back of the guitar.

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Shielding is used to reduce 60 cycle hum mainly from single coil pickups as found in Strats. It does nothing for Humbuckers which do not suffer from hum.

Not true. Even a humbucker is susceptible to induced hum and noise' date=' although less so than a single-coil. You also have to consider the controls, although since the wiring is short and mostly shielded, and the pots have little metal canisters shielding them, it's not [i']that[/i] critical. I would say that in most cases with humbucker-equipped guitars the benefits of such intensive shielding won't justify the cost and/or hassle of doing the job, even though there will be an improvement.

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How would you set up a faraday's cage on a semi/SC?

 

Wow, scratched my head for a moment there... As Rotcan said it will be difficult. I suppose you could sow a copperfoiled envelope or bag that would fit through the ƒ-holes if big enough.

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Oh yeah. Just imagine the joy of trying to get a copper bag full of pots, a switch, and a jack all into the correct place. Shudder. I get tense enough as it is working on semihollows; a job like that would probably put me in an asylum! As they say in Jersey, fugeddaboudit...

 

I suppose that the Tom DeLonge ES333 sig would lend itself well to this kind of modification though since it has the access panel.

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You would line the pickup cavities with copper foil; then you would need to have some kind of metal box that the controls could live in since there's no actual 'cavity' in the sense of a solid body guitar. Note that some Les Pauls have this metal box inside their control cavities.

 

Like this' date=' from a 1977 LP Custom:

 

[img']http://i13.photobucket.com/albums/a298/thork86/LPcustom.jpg[/img]

 

 

And underneath:

 

LPcustom001.jpg

 

Pretty horrible :-

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Great' date=' informative thread.

 

I see how the shield works for solid bodies, but we have a lot of semi owners with SC pups here. How would you set up a faraday's cage on a semi/SC?[/quote']

 

I don't know if these are practical in your circumstances, but any of them should work - as far as it goes. (Tongue in cheek offering here, just in case).

 

Buy a pint of shielding paint, pour it into an f-hole and roll the guitar around, front, back, sides, and the excess will run out the f-holes when you turn it upside down to coat the inside of the top!

 

Slightly more serious, use a airbrush and spray every inch of the inside you can see from the f-holes, pickup cavities, etc., with copious quantities of the aforementioned shielding paint.

 

Build your own. Carverman did it. Install 97 rolls of shielding tape to the interior of the body just before final assembly.

 

Paint your music room with shielding paint and only play inside! With the door shut! Don't forget to remove all the florescent light fixtures and then ground the ceiling!

 

Wrap the whole guitar in aluminum foil! I have it on good authority that stops cosmic rays!

 

BUILD the guitar out of metal and let it be its own cage! Oh, that's a dobro, isn't it? Are they any quieter?

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